The Swiss city of Geneva and the Italian capital of Rome have been named the permanent seats of the Rotterdam Convention on chemical substances.
The German city of Bonn, which was also a candidate, lost the vote on Friday at the end of a five-day conference, chaired by the Swiss environment agency, in Geneva.
"This decision is very positive as it means the Convention will be able to work with the other international conventions and organisations based in Geneva," said the agency's director, Philippe Roch.
"For some time now, the Swiss cabinet and parliament have made the environment one of their top five foreign policy priorities and this decision confirms our position as an international environmental hub," he told swissinfo.
The Rotterdam Convention aims to reduce the health and environmental risks of hazardous chemicals by regulating the import and export of such products – especially in developing nations.
Geneva and Rome have managed the secretariat of the Convention together since 1998 and submitted a joint candidature for the permanent seat.
Both the Swiss and Italian governments lobbied hard for the vote, arguing that the two cities represent centres of “international expertise” in the field of dangerous substances.
"When it comes to chemicals, Geneva is the centre for international environmental agreements and it would have been a pity if that centre had been broken up," said Beat Nobs, of the Swiss environment agency.
"This decision makes sense both financially and logistically," he told swissinfo. "And ultimately, it strengthens Switzerland's commitment to the environment."
Geneva is home to the United Nations Environment Programme (UNEP) and a host of other UN agencies involved in the regulation of chemical products.
Pesticides are the particular concern of the UN Food and Agriculture Organization (FAO) in Rome.
At a press conference in Geneva on Friday, both sides hailed the decision as evidence of the international community’s desire to achieve greater coherence and synergy when it comes to international agreements.
"Rome is very happy with the success of this conference," said Italy's ambassador to the conference, Paolo Bruni.
"We're very satisfied with the outcome of the vote because it will contribute greatly to realising the objectives of this Convention," he added.
Swiss environment experts, along with top officials from the UNEP and the FAO, also said the week-long talks had been successful in reducing the risks of industrial poisons.
“Governments have given the Rotterdam Convention an enthusiastic vote of confidence,” said the FAO’s assistant director-general, Louise Fresco.
“This is an extremely important issue, especially for developing countries because the use of pesticides is only going to increase as the world’s population grows,” she added.
The gathering also agreed to extend the list of chemicals and pesticides regulated by the treaty, which entered into force on February 24.
Ministers and officials from the Convention’s 76 signatory states decided to add 14 new hazardous substances – including a lead additive used in petrol – to an existing international “watch list” of 27 products.
A total of 41 poisonous products are now subject to limitations.
They did not, however, include toxic asbestos, which is still used in construction – particularly in the developing world – on the list.
This prompted suggestions by conservationist organisations, like the WWF, that the Convention had been weakened by the lack of action on asbestos.
"I do not believe that this is a serious undermining of this Convention," said the head of the UNEP, Klaus Töpfer.
"Asbestos is not a closed case,” he added. “We have to do more to convince [the doubters] that it should be handled as the other 41 on the list.”
There are up to five million cases of pesticide poisoning every year worldwide, resulting in several thousand deaths among farm workers, mostly in developing countries.
Some 70,000 different chemicals are available on the market today and around 1,500 new ones are introduced every year, making it difficult for many countries to monitor and manage potentially dangerous substances.
Developing nations use only 25 percent of world pesticide output, but they account for 99 percent of registered deaths.
Under the provisions of the Rotterdam treaty, authorisation to export the most hazardous chemical pesticides and products will no longer be granted unless the importing country gives its prior informed consent.
swissinfo, Anna Nelson in Geneva
The Rotterdam Convention applies to chemical products that are banned or severely restricted, as well as to extremely hazardous pesticides.
It aims to improve human and environmental security by reducing the risks of industrial chemicals and pesticides.
There are now 41 such dangerous substances on the treaty’s watch list.